New York real estate heir Robert Durst took the witness stand in his own defense in a Los Angeles County court Monday – a move considered risky for a defendant in a murder trial.  

Durst, 78, is charged with killing his best friend Susan Berman, who was shot and killed in her home in 2000.

Appearing frail and softspoken, Durst was wheeled over to an area next to the witness stand. His lead attorney, Dick DeGuerin, sat in front of him, and asked: "Bob, did you kill Susan Berman?"

"No," Durst replied. 

"Do you know who did?" 

"No, I do not." 

Earlier, prosecutors resumed their cross-examination of the only other defense witness, false memory expert Elizabeth Loftus, to begin the day.

CLICK HERE TO GET THE FOX NEWS APP

Durst’s testimony is expected to last several days.

This is a developing story. Check back for updates. 

The Associated Press contributed to this report.